It is common in transducing electronic music to employ a rotating loudspeaker, or a stationary loudspeaker and a moving horn or reflector, to produce a rotating acoustic radiation pattern, the rotation rate being about 6. or 7. rps., or less, and the motion being such as to develop Doppler variations in frequency. Such devices provide pleasing effects, the tones being both frequency and amplitude modulated. In such systems, it is common to provide variations in frequency of rotation. However, the cost of a mechanical system is considerable in relation to the cost of a common electronic organ.
It is an object of the present invention to provide a wholly electronic system for simulating the audio effects produced by a mechanically rotating acoustic source which is designed to produce Doppler variations in frequency.
It is another object of the invention to provide a system in which (1) flute and (2) other output tones, of an electronic organ, are independently modulated in frequency and amplitude and radiated via separate spatially separated loudspeakers.
The system employs cascaded frequency modulators and amplitude modulators, the latter controlling expression and also introducing tremolo.